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Schulung MariaDB/MySQL für Fortgeschrittene im August 2019 in Köln

Sommerferien-Zeit – für all die Daheimgebliebenen dürfte es jetzt hoffentlich etwas ruhiger zu und her gehen. Zeit für eine Weiterbildung? Es bleibt nicht mehr viel Zeit, das Jahres-Schulungs-Budget aufzubrauchen!

Vom 19. bis 23. August führt FromDual wieder einmal die Schulung MariaDB und MySQL für Fortgeschrittene in Köln durch. Siehe auch unsere Schulungstermine.

Enable General Query Log per Connection in MariaDB

The General Query Log in MariaDB is a Log (file or table) that logs every statement sent from the Application to the MariaDB Database Server from the Connect Command to the Quit Command. A simple example you can find here:

MariaDB sys Schema

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The MySQL sys Schema is a cool thing and was mostly developed by Mark Leith and Jesper Wisborg Krogh from Oracle/MySQL.

Oops! - That SQL Query was not intended... Flashback

It is Saturday night at 23:19. Time to go to bed after a hard migration day. Just a last clean-up query before finishing: Tap tap tap. Enter! - Oops!

SQL> UPDATE prospect_lists_prospects SET prospect_list_id = '73ae6cca-7b34-c4a3-5500-5d0e2674dbb6';
Query OK, 4686 rows affected (0.21 sec)
Rows matched: 5666  Changed: 4686  Warnings: 0

A verification query to make sure I am in the mess:

Do not underestimate performance impacts of swapping on NUMA database systems

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If your MariaDB or MySQL database system is swapping it can have a significant impact on your database query performance! Further it can also slow down your database shutdown and thus influence the whole reboot of your machine. This is especially painful if you have only short maintenance windows or if you do not want to spend the whole night with operation tasks.

Dropped Tables with FromDual Backup Manager

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Some applications have the bad behaviour to CREATE or DROP tables while our FromDual Backup Manager (bman) backup is running.

This leads to the following bman error message:

FromDual Ops Center for MariaDB and MySQL 0.9.1 has been released

FromDual has the pleasure to announce the release of the new version 0.9.1 of its popular FromDual Ops Center for MariaDB and MySQL focmm.

The FromDual Ops Center for MariaDB and MySQL (focmm) helps DBA's and System Administrators to manage MariaDB and MySQL database farms. Ops Center makes DBA and Admins life easier!

FromDual Ops Center for MariaDB and MySQL 0.9 has been released

Caution: We have introduced an evil bug which prohibits installation of focmm. Sorry! Somehow it did pass our QA. To fix this bug update file lib/ on Line 1965 as follows:

- $sql = sprintf("REPLACE INTO `focmm_configuration` (`key`, `value`) VALUES ('%s', '%s'), ('%s', '%s'), ('%s', '%s')"
+ $sql = sprintf("REPLACE INTO `focmm_configuration` (`key`, `value`) VALUES ('%s', '%s'), ('%s', '%s')"

In the meanwhile we prepare a new release.

MariaDB Prepared Statements, Transactions and Multi-Row Inserts

Last week at the MariaDB/MySQL Developer Training we had one participant asking some tricky questions I did not know the answer by heart.

Also MariaDB documentation was not too verbose (here and here).

So time to do some experiments:

Uptime of a MariaDB Galera Cluster

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A while ago somebody on Google Groups asked for the Uptime of a Galera Cluster. The answer is easy... Wait, no! Not so easy... The uptime of a Galera Node is easy (or not?). But Uptime of the whole Galera Cluster?

My answer then was: "Grep the error log." My answer now is still: "Grep the error log." But slightly different:

Linux system calls of MySQL process

We had the problem today that a MySQL Galera Cluster node with the multi-tenancy pattern caused a lot of system time (sy 75%, load average about 30 (you really must read this article by Brendan Gregg, it is w

MariaDB and MySQL Database Consolidation

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We see at various customers the request for consolidating their MariaDB and MySQL infrastructure. The advantage of such a measure is clear in the first step: Saving costs! And this request comes typically from managers. But what we unfortunately see rarely is to question this request from the IT engineering perspective. Because it comes, as anything in life, with some "costs". So, saving costs with consolidation on one side comes with "costs" for operation complexity on the other side.

FromDual Performance Monitor for MariaDB and MySQL 1.0.2 has been released

FromDual has the pleasure to announce the release of the new version 1.0.2 of its popular Database Performance Monitor for MariaDB, MySQL, Galera Cluster and Percona Server fpmmm.

The new FromDual Performance Monitor for MariaDB and MySQL (fpmmm) can be downloaded from here. How to install and use fpmmm is documented in the fpmmm Installation Guide.

MariaDB and MySQL consulting by plane

Since January 2019 FromDual tries to contribute actively a little bit against global warming too.

The best for the climate would be to NOT travel to the customer at all! For this cases we have our FromDual remote-DBA services for MariaDB and MySQL.

MySQL Enterprise Backup Support Matrix

MySQL Enterprise Backup (MEB) is a bit limited related to support of older MySQL versions. So you should consider the following release matrix:

MariaDB/MySQL Environment MyEnv 2.0.2 has been released

FromDual has the pleasure to announce the release of the new version 2.0.2 of its popular MariaDB, Galera Cluster and MySQL multi-instance environment MyEnv.

The new MyEnv can be downloaded here. How to install MyEnv is described in the MyEnv Installation Guide.

Using tmux for MariaDB database support and surveillance

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See also Byobu.

See also our older article: Using screen for support and/or surveillance.

First simple steps

The command tmux starts a tmux server and opens a new session with a (pseudo) terminal:

shell> tmux


To NULL, or not to NULL, that is the question!

As we already stated in earlier articles in this blog [1 and 2] it is a good idea to use NULL values properly in MariaDB and MySQL.

UNDO logs in InnoDB system tablespace ibdata1

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We see sometimes at customers that they have very big InnoDB system tablespace files (ibdata1) although they have set innodb_file_per_table = 1.

So we want to know what else is stored in the InnoDB system tablespace file ibdata1 to see what we can do against this unexpected growth.

First let us check the size of the ibdata1 file:

MariaDB indexing of NULL values

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In the recent MariaDB DBA advanced training class the question came up if MariaDB can make use of an index when searching for NULL values... And to be honest I was not sure any more. So instead of reading boring documentation I did some little tests:

Search for NULL

First I started with a little test data set. Some of you might already know it:

MariaDB/MySQL Schulungstermine 2019

Jetzt sind auch noch die letzten MariaDB und MySQL Schulungstermine für 2019 festgelegt und veröffentlicht.

Mit unseren drei Schulungspartnern in Essen, Köln und Berlin bietet FromDual zur Zeit insgesamt 12 öffentliche Schulungen zum Thema MariaDB und MySQL an.

Es sind dies:


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